The present invention relates to a battery pack for housing plural secondary batteries inside a case.
Conventionally, the inside of a battery pack for travel used in an electric vehicle or a hybrid vehicle is equipped with plural battery modules. The battery module is an assembled battery made by mutually connecting plural battery cells (cells). By managing multiple battery cells in a battery module unit, proper arrangement density or heat dissipation properties of the battery cells are ensured while increasing a total output voltage of the whole battery pack.
In each of the battery modules, a cell monitoring unit (CMU) is installed as an electronic controller for acquiring, managing and monitoring temperatures or voltages of the individual battery cells and controlling and processing all or a part of the A/D conversion. For example, variations in voltage originating from charge and discharge characteristics of the individual battery cells are equalized in the battery module unit by the cell monitoring unit.
On the other hand, a battery management unit (BMU) for supervising all the battery modules is annexed as an electronic controller higher than the cell monitoring unit. The battery management unit manages a state of charge (SOC) or a state of health (SOH) of the whole battery for driving based on information about the battery cell managed in each of the cell monitoring units. A computation load is reduced by differentiating functions or the contents of control in each of the electronic controllers in this manner.
Incidentally, information acquired in the cell monitoring unit is aggregated in the battery management unit located in its high hierarchy, and is transferred to various electronic controllers of the vehicle side through a vehicle-mounted communication network. In many cases, the information acquired in the cell monitoring unit cannot be read out directly unless the information passes through the battery management unit. As a result, when a failure occurs in the battery management unit, it becomes difficult to grasp states of the individual battery cells.
In order to solve such a problem, a review of forming a connector for directly acquiring information from the battery cell of the inside of the battery pack is made. For example, it is contemplated to previously form a connector for external connection into which a probe is inserted in a position just over a positive terminal and a negative terminal of the battery cell in an outer surface of the battery pack. Such an idea can acquire information about the battery cell without passing through the battery management unit (see Patent Reference 1).
[Patent Reference 1] JP-A-2011-169870